Load distribution or load spreading is a method by which network resources such as bandwidth are more effectively utilized and overall performance is improved in a network. Most automated load distribution and load spreading techniques deployed today operate with only a very local view. These load distribution and load spreading techniques only consider the number of next hops on the shortest path to a given destination and do not consider the overall distribution of traffic in the network.
Equal cost multi-path (ECMP) is a common strategy for load spreading of unicast traffic in routed networks that can be utilized where the decision as to how to forward a packet to a given destination can resolve to any of multiple “equal cost” next hops, which tied for being on the shortest path when running database calculations. ECMP can be used in conjunction with most unicast routing protocols and nodes equipped with the required supporting data plane hardware. It relies on a per hop decision that is local to a single router and assumes a complete forwarding table at every intermediate node. Using ECMP at any given node in a network, the load is divided pseudo-evenly across the set of equal cost next hops. This process is implemented independently at each hop of the network where more than one path to a given destination exists.